Screw-cutting machine



(ModeL) 2 SheetsSheet 1.

J. KAYLOR.

SCREW CUTTING MAGHINE.

No. 245,507. Patented Aug. 9,1881..

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2 R 0 L Y A K J SCREW CUTTING MACHINE.

No. 245,507. Patented Aug. 9,1881.

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J OSEPHKAYLOR, OF ALLEGHENY, ASSIGNOR T HIMSELF AND JAMES VERNER, OF PITTSBURG, PENNSYLVANIA.

SCREW-CUTTING MACHINE.

SPECIFICATION formingpart of Letters Patent No. 245,507, dated August 9, 1881,

Application filed July 6,1880. (ModeL) A To alt whom it may concern Be it known that I, JOSEPH KAYLOR, of Allegheny, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Screw-Gutting Machines; and I do hereby declare the following to be a full, clear, and exact descriptiontbereof, reference being had to the accompanying drawings, forming part of this specification, in

IO which Figure 1 is a side elevation of my improved screw-cutting machine. Fig. 2 is a plan view of the tripping device for tripping the die-head and releasing the rod after the screw is cut.

r5 Fig. 3 is an under-side view of the same, illustrating its motion by broken lines. Figs. 4 and 5 are sectional views, showing the construction and operation of the die-head. Fig. 6 is a face view of the head,and Fig. 7 is a sectional view of the head on the line y 3 of Fig. 6, and also shows a modified form of the insetting device.

Like letters of reference indicate like parts in each.

My invention relates to an improvement in machines for cutting threads on rods, boltblanks, tubes, &c., and it consists, mainly, in forming the die-carrier lugs by which the insetting or offsetting of the dies is accomplished on both inner and outer faces with two straight o surfaces connected by an incline, and in combining therewith a collar having an annular recess or groove whose walls correspond with the lugs, whereby the insetting as well as the offsetting of the die is perfectly controlled and 5 the dies caused to describe a true circle; and,

secondarily, in details of construction hereinafter more fully set forth.

The machines known to me in general use are defective for several reasons: In the first 40 place, the screw-cutting die-heads, not being secured rigidly against inward motion, will,

after having taken a bite in the rod, follow a defect therein and cut the thread of equal depth around its entire circumference, whether 5 the diameter of the rod is the same or not in all directions. This is especially the case where the dies are new and sharp, as their tendency is to draw into the rod after taking the bite. This tendency is diminished, however, as the dies become dull. In such prior machines provision is made for preventing the dies from being pressed outward, but no provision for preventing the insetting of the dies upon the rod. They are also defective in that the devices used for operating the dies are generally levers and springs, which are subject to displacement,imperfect operation, and distortion,

so that they soon become defective and often inoperative.

The dies heretofore used are made with a central score or groove running across the threads; but thisconstruct-ion isobjectionable for the following reasons: The die is first cut or scored andthen tempered, and in being tempered is liable to crack and break, the fracture 6 5 running from the central groove, as indicated by the dotted line a, Fig. 6. When the dieis sharpened the temper has first to be drawn, and in hardeningit is again subjectto the same danger of breakage, and, further, it can be sharpened only by the use of a grindstone provided with a bead or projection fitting into the groove, which is similar in form to groove 37.

Thedie-carriershaveheretoforebeen secured in the head by means of set-screws and-other adjusting devices which are designed to take up the wear of the parts 5 butexperienceproves that when this wear occursit is extremely difficult to take up the slack so producedin such a manner as to have a perfect adjustment of 8c the die. The result is that the cutting is defective.

To enable others skilled in the art to make and use my invention, I will now describe its construction and mode of operation. 8

The head 1 is mounted on the end of a rotatin g shaft, 2, and is providedwith two or more pairs of dies, 3, as may be desired. The dies3 are straight pieces of steel, having the usual grooved cutting-face, 3 but they differ from 0 the old form in that the central transverse groove, 37, is not made in the face of the die, but in this case is formed between each pair by placing a liner, 38, between them. The reasons for forming the dies in this way are 5 that they are more easily made, repaired, and sharpened, and not exposed to breakage in tempering. They are secured in die-carriers 4, which slide radially in grooves 16 in the head by set-screws17, which extend through slots in 109 the walls of the groove 16, and they are adjusted therein by means of set-screws 5. The die-carriers 4 are dovetailed in cross-section, and are secured in the head 1 by gibs or wedgeshaped keys 6, which are fastened by screws or bolts 7.

On the back end of each die-carrier 4 is a projection or lug, 8, having an outer inclined surface, 9, and a straight end, 10, and having an inner straight side extending to a point about opposite to the foot of the outer incline, 9, and then an incline surface, 12, and beyond that a short straight face, 13.

Upon the shaft 2, back of the head, is a sliding collar, 14, in the face of which is a circular groove, 15, the outer wallof which corresponds in shape to the outer face of the lug, and the inner wall is parallel to the outer wall. The inner sides of the lugs being cut out, as described,by the continuation of thelong straight side 11 nearly to the end, they are enabled to 7 enter the groove and pass into its inner extremity without impediment.

The effect of the movement of the sliding collar up to the head 1 is to cause the lugs S to enter the groove 15 until the walls thereof come in contact with the outer inclined sides, 9, and then the die-carriers 4 are forced inward toward the center of the head by the effect of' theinclined surfaces ofthe collar-groove upon the lugs. It will be seen that when the lugs have thus entered the groove 15 the diecarriers are held rigidly in the head in a certain fixed relation to each other, and that they cannot move in toward or out from the central point of the head as long as the sliding collar 14 remains in contact therewith. The effect of the parallel sides of the lugs bearing against the corresponding parallel surface of the collar is the same as a friction-clutch, and preven is the collar from sliding back on sh aft2. The result of this construction is that when the rod, bolt-blank, tube, or other article is placed in the dies and the head is rotated the cutting edges or teeth of the dies will describe a perfect circle thereon, and that the dies cannot be drawn in by the draft of the cut or forced out by the pressure of the iron upon them, so that, whatever may be the shape of the rod or however untrue its circumference may be to a circle, the bottom of the thread cut therein will be a perfect circle and will afford a true bearing to a properly-cut nut or sleeve.

1 secure the die-carriers 4 in the grooves 16 of the head 1 by means of gibs 6, which are wedge-shaped in cross-section, and which are fastened to thehead by bolts 7 passing through them.

In case of the wearing of the die-carrier in its movement in the head, the slack thereby produced may be taken up, either by grinding off the bottom of the gibs 6 and dropping them a little lower in the heads, or by insertin g a sheet of tissue-paper or other thin medium as a liner between the outer sides of the gibs and the portion of the head which surrounds them.

The head is secured to the shaft 2 by means of a screw-nut, 1S, placed thereon, and this shaft is mounted in a suitable frame, 19, and is driven by a pulley, 20, or other power device.

Instead of placing two dies, 3, in a single carrier and separating them by liners, each die 3 may have an independent carrier, and they may be placed at any desired distance apart in the head. If the sides of the groove 15 become worn by the lugs 8, the collar 14 may be turned enough to cause the lugs to work on a new place.

The collar 14 is provided upon the outer flange, 21, with an inclined surface, 22, which is designed for causing it to be retracted and the dies released at the instant when the thread on the rod or tube is finished. The dc vice which I have attached to my machine for accomplishing this purpose consists of the de tent-disk 23, mounted upon a suitable shaft, and provided with a weighted lever, 24, which, when it is released, will cause the detent-disk to turn.

Pivoted on the side of the frame of the machine is a pawl, 25, which, when in position, stands vertically, with its lower end resting in the notch 26 in the detent-disk 23, and with its upper end extending across the path of the rod or tripping device 27. The rod 27 is attached to the head 28, which carries the rod or tube upon which the thread is being cut as it is fed to the dies.

Attached to and extending up from the cam 23 is an arm, 29, to which is attached an offsetting-slide, 30, having offsets or wedges 31 31 upon its opposite edges. Upon the releasing of the detent-disk 23 and the dropping of the weighted lever 24 the slide 30 is drawn backward, and the wedge or inclined surface 31, pressing against a shoulder, 36, on a sliding bar, 32, forces the bar 32 inward toward the rotating collar 14, where, coming in contact with the incline 22, it forces the sliding collar backward on the shaft 2 and away from the head. This retraction of the sliding collar causes the dies 3 to be forced out and release the rod or tube, so that it can be removed from the machine.

Pivoted in the bed-plate or frame of the machine is a lever, 33, which, being provided with a bifurcated arm working in a groove, 35, in the sliding collar 14, is the means used to throw the collar forward against the head and bring the dies into a working position when a rod or tube is inserted in the machine. The same movementof the lever 33 which passes between lugs or projections 35 on slide-bar 30 causes the slide 30 and bar 32 at the side of the machine to be moved back into their proper position and raises lever 24, which brings the detent-disk 23 around, so as to be caught by the pivoted pawl, as shown in Fig. 1.

It is apparent that a greater number than two dies may be used in the head, and also that my machine is not open to the objection of movable and fragile parts, which is so justly urged against many machines now in use, and that when the dies are set they cannot be moved either in or out from their position without retracting the sliding collar.

In many machines now in use the cuttings, getting in between the sliding dies and their carriers,produce wear, and consequentlylooseness and an irregular operation, of the dies. This is entirely obviated in my construction, as the cuttings cannot get access to the groove 15, by which the dies are projected toward and retracted from the center.

Other advantages of my construction are its great simplicity and strength, and consequent saving in the first cost of the machine and in repairs.

Fig. 7 shows a modified form of the collar and the head. In this the sliding collar projects at its outer edges over the outer edges of the head. This modification effects a reduction of cost in the construction of the head and a saving of material over the form shown in Fig. 4.

I am aware that die-carriers having inclined lugs, in combination with a sliding collar having correspondingly-inclined recesses for the reception of the lugs of the die-carriers, have heretofore been devised for insetting and offsetting the dies, and also that the lugs of the die-carriers have been provided with square portions to bind with the outer ring of the collar and prevent any displacement due to the tendency of the dies to separate when in opertion, and do not herein claim the same; but I am notaware that any provision has heretofore been made to insure the dies describing a perfect circle, and to prevent the inward motion of the dies when the surface of the rod operated upon is irregular and imperfect. Therefore What I claim as myinvention, and desire to secure by Letters Patent, is

1. In a machine for cutting screws, a die-carrier provided with a 1n g projecting at right angles, having an outer surface which is first straight, then inclined inward, as at 9, and lastly straight, as at 10, and an inner straight side, 11, reaching to the foot of the incline 9, an inclined surface, 12, and a short straight surface, 13, in combination with a sliding collar having a recess which corresponds in shape to the outer face of the lug, substantially as and for the purposes described.

2. In a screw-cutting machine, the combination, with die-carriers having projecting lugs with inclined surfaces, of a sliding collar havin g a continuous circular groove, the walls of which correspond to the inclined faces of the lugs upon the die-carriers, substantially as and for the purpose specified.

3. The combination, with the rotating head and sliding die-carriers, of the sliding collar 14, provided with the inclined surface 22 or cam-flange 21, and the movable bar 32, substantially as and for the purpose specified.

4. The combination, with the rotating head and sliding die-carriers, of the sliding collar 14, having the inclined surface 22 or cam-flan ge 21, the sliding bar 32, the offsetting-slide 30, having the inclines 31 and 31 for actuating the sliding bar, the pawl and weighted detentdisk, and the sliding head provided with the tripping-rod, substantially as and for the purpose specified.

5. The combination, with the rotating head and sliding die-carriers, of the sliding collar havingthe inclined surface 22 or cam-flange 21, the sliding bar 32, the ofi'setting-slide 30, and the pivoted lever 33, connected to and adapted to operate both the sliding collar let and the offsettingbar 30, substantially as and for the purpose specified.

In testimony whereof I have hereunto set my hand.

JOSEPH KAYLOR.

Witnesses:

J AMES K. VERNER, T. B. KERR. 

